Multiselectors employing crossbar switches having split horizontals or selection levels



Nov. 12, 1968 J. P. 1.. BASSET T 3,410,952 I MULTISELECTORS EMPLOYING CROSSBAR SWITCHES HAVING SPLIT HORIZONTALS OR SELECTION LEVELS Filed July 8, 1965 6 Sheets-Sheet l Nov. 12, 1968 p L, BASSET ETAL 3,410,962

MULTISELECTORS EMPLOYING CROSSBAR SWITCHES HAVING SPLIT HORIZONTALS OR SELECTION LEVELS Filed July 8. 1965' 6 Sheets-Sheet 2' Nov. 12,1968 BASSET ET AL 3,410,962

MULTISELECTORS EMPLOYING CROSSBAR SWITCHES HAVING SPLIT HORIZONTALS OR SELECTION LEVELS Filed July 8, 1965 6 Sheets-Sheet 5 sr/c 572C r'' F? 0 2 Pr smd b h Z n 772* LW/ s 5 C5 5m 522/ f5 g) 1 Nov. 12, 1968 J. P. L. BASSET ET AL 3,410,962

MUL'IISELECTORS EMPLOYING CROSSBAR SWITCHES HAVING SPLIT HORIZONTALS OR SELECTION LEVELS Filed July 8, 1965 6 Sheets-Sheet 5 CEC W F/ r 15w Zi O/C/O/ COC 4: 5 m; LCCCOJ Mp] I CE CE 2? United States Patent 3,410,962 MULTISELECTORS EMPLOYING CROSSBAR SWITCHES HAVING SPLIT HORIZONTALS 0R SELECTION LEVELS Jacques Pierre Louis Basset, Paris, and Marcel Pierre Bohner, Epinay-sur-Orge, France, assignors to International Standard Electric Corporation Filed July 8, 1965, Ser. No. 470,437 Claims priority, application France, July 10, 1964, 981,433; July 31, 1964, 983,801 14 Claims. (Cl. 179--22) ABSTRACT OF THE DISCLOSURE Improvements are provided in crossbar telephone systems in which light traflic is encountered regularly over certain lines while normal or heavy traffic is usual on other lines. The lines carrying normal trafiic are connected to terminals of a cross-bar switch so that contact can be completed (over the horizontals or selection levels) to all the selectors. Those lines carrying light tralfic are connected to terminals so that connection may be completed to only a few of the selectors. The number of lines carrying light traffic which can be connected is doubled in this way. The result is a crossbar switch connected to far more lines than is usual, thus affording savings in material and space. The invention also enables the incorporation of both selectors and register finders on a single cross-bar switch to effect great savings in equipment and costs.

This invention is concerned with improvements to selection systems for circuits or electrical equipments and more particularly, to selection systems using cross-bar switches.

A crossbar switch or multiselector has a certain number of individual selectors each having an inlet and a certain number of outlets or selection levels. In order to prepare the connection between the inlet and one of the outlets, horizontal selection bars are used. The operation of some of the selection bars enables choosing a selection level. Next, in order to establish the connection, a vertical connection bar is operated. The horizontal bars extend transversally in front of all the individual selectors of the multiselector and prepare a selection for all the selectors at once, but the connection takes place only in the selector having the vertical bar operated. Then the selection bars can be released; the connection remains established as long as the vertical bar is not released.

A selector of this type enables also the selection and interconnection of various outlets. In this case, the inlet is not used.

Such multiselectors are used, for example, in a telephone exchange to connect two subscribers lines to a common equipment called feeder, during a call. The feeder is connected to two selectors of a primary stage (primary selectors). By means of one of the two selectors (call finder), it can reach a selector of a terminal stage (terminal selector), which gives access to the calling subscribers line. The connection of the called subscribers line is done by means of the other primary selector of the feeder (connector) oriented onto another terminal selector giving access to the called line.

In a certain number of telephone systems, each terminal selector gives access to a group of subscribers lines. This means that the individual selectors of the multiselector have their outlets multipled one by one and that the number of outlets of the multiselector is equal to the number of outlets of an individual selector. The number of inlets of the multiselector is equal to the number of selectors. In order to most economically adapt the equipment to the subscribers traffic the number of selectors varies with every individual case. This is not fully satisfactory, as the selection device (horizontal bars) remains the same in every case and thus are used ineificiently when the traffic is low. The inefficient usage is aggravated since the normalized bays containing the multiselectors are of constant width provided for maximum traffic, thus the space requirement of the installation is not reduced when the number of terminal selectors per group of subscribers lines decreases. Besides, the trafifie of the subscribers" lines is very variable according, on one hand, as to what purpose they are used (professional or private) and, on the other hand, according to the hour and the day. In order to take into account this fact, it is a customary practice to include, inside the group of subscribers lines handled by a same multiselector, lines of varied nature, so as to obtain a stretching out of the traffic. Nevertheless, the use of the equipment supplied is as yet imperfect; since the same number of selectors are used for the small-tralfic lines as for the large-traffic lines.

The feeder function comprises feeding the lines of the two subscribers called and calling; sending the ringing current and the ringing tone and holding the two connection chains. For sending the dial tone, receiving the called subscribers code and controlling the selections, a specialized unit called a register must be connected to the feeder. In well-known and currently used telephone systems, this connection is made by means of selectors called register finders.

The number of feeders is a function of the total traffic of the subscribers of the installation. The number of primary selectors is also determined by the total trallic usually there are two per feeder. The primary selectors are grouped in frames housed in bays of determined size, it is obvious that the available room is wholly utilized when the total number of primary selectors of the installation is an exact multiple of the number of selectors that a frame can receive. The case is scarce, generally there are empty spaces in the primary stage frames.

Each primary selector frame has its own selection systems and a multiselector. Its operation is very quick. Since the number of connections it must establish its comparatively small, the selection system of a multiselector is generally not used optimally.

In well-known and currently used systems, the register finders are grouped into independent frames also having their own selection system, which results in the same lack of utilization of the available space and of the installed material.

On the other hand, grouping the register finders is inconvenient from the viewpoint of reliability and necessitates expensive precautions to avoid accidentally putting a multi-selector out of service.

The present invention is therefore concerned with improvements to selection systems enabling, by a new means of distributing the lines on the selectors of a terminal selection stage, and new dispositions of the register, finders increased reliability, more efficient employment of the space available and the reduction of the equipment used. All of this of course, enables a reduction of the cost of the installation.

One of the objects of the invention is to provide a selection system comprising at least one primary selector stage, at the inlets of Which are connected the feeders, and register finders for connecting feeders to registers. Means are provided for associating each group of primary selectors with at least one group of register finders. These groups of selectors are part of the same multiselector as are the primary selectors and are controlled by a single selection system.

According to another object of the invention, the feeders are connected to calling lines by means of certain prirnary selectors of a multiselector, are also connected to register finders of this multiselector, so that each feeder, for the operation of the primary selectors and register finders which it uses is connected to a single multiselector and that the defect of a multiselector render unavailable only a single group of feeders, which minimizes the influence of breakdowns.

A feature of the invention lies in the fact that the feeders connecting themselves to the calling lines by means of certain primary selectors of a multiselector are connected to the called lines through other primary selectors of the same multiselector, for the same reliability reasons.

According to another feature of the invention, each register finder is a selector the outlets of which are divided into at least two groups, a first group of outlets to which are connected feeders and a second group of outlets to which are connected registers. The connection of a register to a feeder requires simultaneous selection of two outlets, one of a feeder, the other of a register, after which the connection connects to each other the two selected outlets.

According to another feature of the invention the different register finders of a group have their homologous outlets multipled, thus giving access to the same feeders and registers, and can be utilized independently to connect one of the feeders to one of the registers.

According to another feature of the invention, a same register is multipled on the outlets of two or more multiselectors, which improves the availability of the registers and the reliability of the operation, a register remaining good for use even when a multiselector is faulty.

According to another feature of the invention, when a group of feeders is requested to serve a call, means are provided to order first the selection of a free feeder by the selection device of the multiselector assigned to the group feeders, then the selection of a free register, any one of the free register finders being then operated to connect the feeder to the register.

According to another feature of the invention when the preceding selections are realized, a switching device operates to preclude any other similar operation and prepare the use of the multiselector to connect the feeder to the calling line.

According to another feature of the invention, when the selected feeder is actually connected to a register, the selection device is released, and this enables it to be used for the selections whose object is to connect the feeder to the calling line.

Another object of the invention is to provide a selection system in which a group of terminal selectors capable on one hand to reach large-traffic lines, each connected to an outlet of all the selectors of the group, and, on the other hand smaller-trafiic lines each connected to an outlet of only certain selectors of the group; so that the lines may have at their disposal a number of connection points in relation to their respective traffic, and that the connection points provided may be utilized at an optimum.

Another feature of the invention is a selection system in which a group of terminal selectors capable of reaching, on the one hand, lines of a first set each connected to an outlet of all the selectors of the group, and, on the other hand, at least two sets of lines of smaller traific. The lines of the second set connected to outlets of certain selectors of the group with the lines of a third set connected to outlets of other selectors of the group.

According to another feature of the invention, the lines from the first set occupy homologous outlets multipled upon all the selectors of the group.

According to another feature of the invention, the lines of the second set occupy homologous outlets multipled upon a part of the selectors of the group, the lines from the third set occupying outlets homologous to the ones from the second set multipled on the remainder of the selectors of the group.

According to another feature of the invention, the lines from the second set are multipled upon outlets of one half of the selectors of the group, the lines from the third set being multipled upon the other half of the selectors of the group.

According to another feature of the invention, when one of the lines from the second set has to be connected, a switching device operates in answer to the marking of the line and causes the test of availability of half of the selectors, those upon which the line is multipled in order to prepare the utilization of one from these selectors only. For a line from the third set, another switching device fulfills the same function in respect to the other half of the selectors.

According to another feature of the invention, when one line from the first set of lines has to be connected, a third switching device operates responsive to the marking of the line and causes the operation of both switching devices already mentioned above, so as to enable the utilization of all the selectors of the group.

Various features will be disclosed from the following description which is given by way of non-limiting example and with reference to the accompanying drawing wherein:

FIG. 1 is the block diagram of a selection system conforming to the invention;

FIG. 2 is the wiring diagram of a terminating multiselector conforming to the invention;

FIG. 3 is the wiring diagram of a primary multiselector conforming to the invention;

FIGS. 4, 4a are the detailed wiring diagram of the essential circuits enabling the control of the multiselector described by FIG. 2; and

FIGS. 5, 5a are the detailed wiring diagram of the essential circuits used to control the multi-selector of FIG. 3.

FIGURE 1 represents a very simplified block diagram of a telephone installation using two crossbar switch selection stages to connect the subscriber lines to the common equipment or feeders establishing and supervising the calls. There are shown two multiselectors of the primary stage MP1 and MP2 and two multiselectors of the terminal stage MTI and MT2. Each multiselector is represented in a rectangle, the vertical lines representing the individual selectors and the horizontal lines the multipled selection levels.

Each feeder, such as AL is connected to two selectors of the primary stage, in the same multiselector. The feeder AL is connected to two primary selectors, a call finder CA and a connector C0 of the multiselector MP1. In a primary multiselector, the selection levels of the primary selectors are all multiplied and give access to terminal selectors, by two levels to two selectors of each terminal multiselector. For example, the multiselector MP1 is connected to the terminal selectors ST 1 and STZ of terminal multiselector MTl.

The subscribers lines are connected to the selection levels of the terminal selectors. As per the present invention it may be seen that, for each terminal multiselector, there are three sets of lines. Lines which, like AB l, are multipled upon outlets of all the selectors of the multiselector; those which, like AB2 are multipled upon outlets of a half of the selectors and those which, like ABS, are multipled upon outlets of the other half of the selectors. Thus, are defined two sub-groups of selectors, and a same primary multiselector are connected to a selector of each sub-group (5T1 and STZ respectively for MP1).

The diagram also shows how a call is established between the line A131 of the terminal multiselector MT! and the line AB-t of multiselector MTZ through feeder AL. The calling subscriber ABl is connected to the feeder AL by the call finder CA and the terminal selector STI. The established connection points are circled. It is obvious that it could have been possible to also establish the connection by means of selector ST2.

Naturally, in order to increase the connection possibilities between a feeder outlet and a determined subscriber line, the present simplified device could be completed by using an intermediate system between primary multiselectors.

When a calling line is connected to a feeder the latter must be associated with a register in charge of sending the dial tone, of receiving the digits dialled and of conducting the selections until the requested call is established. Next, the call is controlled by the feeder that supplies the feeding current over the lines of the connected subscribers, sends the ringing current to the called subscriber and the ringing tone to the calling subscriber, holds the two connection chains, detects the subscribers replacing the handsets and then causes release.

To connect the feeders to the registers, register finders are provided in addition to the primary selectors on the same multiselectors. Feeders such as AL, the call finders CA of which are in the multiselector MP1, are each connected to a horizontal level such as nha of the register finders CE of the same multiselector MP1. To other levels of register finders such as CE, are connected registers. For example, register EN is connected to level nhe. To connect the feeder AL to the register EN, it is necessary to prepare two selections and effect the connection of the register finder CE at the same time on levels nha and nits. In this manner, the two levels are connected to one :another.

It is obvious that the registers are multipled on MP1 and MP2. Thus, when one of the multiselectors is out of service, for any reason, the registers remain accessible through another multiselector. In addition, each group of feeders is associated with a multiselector which is in use only for this group of feeders. Consequently, if the multiselector is put out of service, only the group of feeders associated with it is put out of service at the same time. The perturbation is therefore limited to a minimum.

FIG. 2 shows the wiring of a terminal multiselector such as MTl (FIGURE 1). Two terminal selectors ST1 and ST2 (see FIGURE 1) are represented as well as the connection contacts controlled by a first selection bar BS1 and by the last two selection ba-rs B813 and B814. A horizontal selection bar such as bar BS1 may occupy three positions: a rest position and two active positions (1B and 1H, for BS1). If it is assumed that the bar BS1 is in active position 1B, and then if the vertical bar of selector ST1 is operated, a set of 3 X 3 connection contacts will operate, connecting three lines ([1, l2, [5) of three wires each onto a 3 X 3 vertical conductors of selector ST1. In order to choose between these three lines and to connect only one of them to inlet e1 of the selector, the bars B513 and E814 are used. To connect inlet e1 to line l1, while bar BS1 is put into position 1B, it is necessary to put bar B814 into position. Thus, when the vertical bar is made to operate, inlet e1 is connected of the three conductors of line l1. To connect inlet e1 to line [2, the bar B814 is put into position MB; to connect inlet 21 to line IS the bar BS13 is used, and is put into position 13H.

The above described arrangement provides for connecting three lines for each active position of a selection bar, that is for the twelve first bars 2 l2 3=72 lines. Moreover, it is possible to connect two lines to bar B813 in position 13B, differentiated by the position of bar BS14. Since bar BS13 cannot be put simultaneously to positions 138 and 13H, it is not possible to connect any line to the third level of 13B. A selector has therefore, in total 72+2=74 three-wire outlets.

Besides, as provided by the present invention, certain lines are multipled upon all the selectors of the multiselector, whereas other lines are multiplied only upon half of the selectors. The selector ST1 is part of a sub-group of selectors made up of half of the selectors from the multiselector-those in the right; and the selector ST2 is part of the other sub-group of selectors, those in the left half of the multiselector. The lines from the first set, such as l5, l6, l7, [8, are connected to the outlets in ST1 as well as to those in ST2. The lines from the second set, such as l1, [2, are connected to the selectors in the right, such as ST1. The lines from the third set, such as [3, [4, are connected onto the selectors in the left such as ST2. They occupy the same selection levels as the lines from the second set. Thus, eight lines 11 to 1'8 are connected to the six selection levels of bar BS1. This also applies to bars BS2 to B812, not shown in the figure. Moreover, the two selection levels of bar B813 are also occupied by four lines, so that the multiselector handles, in total, one hundred subscribers lines: forty-eight for the first set of lines, twenty-six for the second, and, twenty-six for the third.

Evidently, other distributions of the selections levels can be adopted according to traffic. It can be contemplated also to allot to the second and third sets of lines two sub-groups of unequal numbers of selectors. The embodiment described in the present specification is only a special example of utilization of the present invention.

The diagram of FIG. 3 shows how a primary multiselector such as MP1 (FIG. 1) is wired. There is represented in FIG. 3 two primary selectors CA, CO, at register finder CE (see FIG. 1), and the connection contacts controlled by the first selection bar BS1 and by the two last selection bars B313 and B514. To illustrate that the invention is not limited to three-wire lines but encompasses lines having any feasible number of wires FIG. 3 shows four-wire lines. Assume that bar BS1 is in the active 1B position, if the vertical bar of selector CA is then activated, a set of 2 X 4 connection contacts is set to connect two four-wire lines (Z1 and 12) to 2 X 4 vertical con ductors of selector CA. To effect the choice between these two lines and connect only one of them to the inlet 21 of the selector, bar B814 is used. In order to connect the inlet 01 to line [1, when bar BS1 is at position 1B, bar B514 must be" at position 14H. In this way, when the vertical bar is set to its make position the inlet e1 is connected to the 4 left-hand vertical conductors, those to which are connected the 4 conductors of line II. To connect the inlet 21 to line [2 the bar B814 is set on position 14B. The arrangement described, therefore, provides for connecting two lines for each of the two active positions of each selection bar, or by the thirteen first bars, 2 13 2=52 lines, the fourteenth bar being used only for switching.

The primary selector CO is identical with the primary selector CA and its outlets are multipled with those of CA. The same holds good for all the primary selectors of the multiselector, but the lines connected to the outlets of the primary selectors are not connected to the outlets of the register finders. The multiplying is broken between the primary selectors and the register finders.

A register finder such as CE does not have any inlets like the primary selectors. It functions to connect to one another two of its outlets. For example, when the bar BS1 is set in position 1B, the operation of the vertical bar of the selector connects the four-wire lines [3 and [3' thus connecting the outlet nha to the vertical conductors. If, at the same time, bar B513 is set in position 13H, the four-wire lines 14 and [4' which constitutes the outlet nhe are also connected to vertical conductors. The outlets nha and nhe are therefore connected to one another which enables connecting the feeder AL to the register EN (see FIG. 1).

All the fourteen bars are used in the same way and each one enables connecting two outlets, one per active position, i.e.: 28 available outlets. One can, for example, provide twenty outlets such as nha connected to twenty feeders (bars BS1 to B810) and eight outlets such as nhe connected to eight registers (bars 13511 to B814).

The number of register finders such as CE, in a same 7 multiselector can vary with relation to the availabilities and the trafiic. The register finders have their levels multipled and can be independently used to answer any call, as they reach the same outlets.

FIG. 4 shows the essential circuits for controlling the operation of a terminal multiselector such as MTl (FIGS. 1 and 2). These circuits enable, in response to the marking of a line to be connected, the positioning of the selection bars for testing the utilizable selectors and for accomplishing the connection.

Every selection bar is controlled by two selection electromagnets which actuate the bar to either one or the other active position. They bear the name already given (FIG. 2) to the positions of the bar, and are represented in the figure by diagonally crossed rectangles. Thus, the selection bar BS1 (FIG. 2) is controlled by the electromagnets 1B and 1H.

Each vertical bar is operated by an electromagnet bearing the name of the selector and represented by a square. FIG. 4 shows the connection electromagnets ST1 and STZ of the corresponding selectors in FIG. 2. Above each connection electro-magnet there appear, for example, two sets of three connection contacts bearing the reference symbol of the electromagnet and followed by a small letter of the alphabet. These contacts are a simplified representation of the two sets of contacts operating in a selector for the connection onto a determined selection level.

The multiselector is controlled by diode and relay circuits. A relay is represented by a rectangle. It bears as reference symbol two small letters followed, where necessary by a number, when the homologous relays are concerned. According to the detached-contact method the contacts of the relays are represented anywhere on the diagram. They bear the reference symbol of the relay which controls them, followed by a number. For instance, the relay te bears the contacts tel and H22 for energizing the relays tfl and tf2. Besides, the selection electromagnets, using the same presentation as the connection electromagnets, control auxiliary contacts. These bear the reference symbol of the electro-magnet followed by a number. It is worth noting that the circuits are current-supplied by a same source, the positive terminal of which is grounded. All the circuits that lead to the other terminal of the current source are terminated by an arrow.

Each subscribers line is provided with an individual equipment or subscribers junctor. The FIG. 3 shows the junctors of three subscribers lines, 1A1, JAZ and 1A3.

The line, equipped with junctor 1A1, is a line from the first set connected onto a level of the selector ST1 and of the selector ST2. It is, for instance, the line 18 in FIG- URE 2. The line equipped with junctor JA2 is from the second set, and can be the line [1 from FIGURE 2. The line equipped with junctor ]A3 is from the third set and can be the line [4 from FIGURE 2. These lines may also correspond, respectively, to the lines of the subscribers AB1, ABZ and ABS in FIGURE 1.

When a subscribers line has to undergo a connection, a marking ground is provided by a circuit not shown in the figure, and a marking contact mq closes in the subscribers junctor. The marking wire which is proper to the line, for instance wire m1, is thus grounded. Since each line has one marking wire, one hundred marking wires are connected through decoupling diodes, such as d1, to the piloting relays tbl to tb8. Each relay, therefore pilots twelve or thirteen lines, as is indicated by the number placed opposite the multiplying arrows.

If it is assumed that wire m1 is grounded, the relay [b4 is energized by the following circuit: battery-contacts tm1.2 and tm2.2contacts tb5.1 and tb6.1relay tb4- contact tb1.4wire m1--contact and mq, ground. Opening of contact tb4.4 prevents the possible energizing of relay tbl. Opening of contact 1124.1 prevents the possible energizing of relays H25 and I126.

Then, the choosing of make contact 1114.1 causes the energizing of relay te which affords for itself a holding circuit through m3, and which through its contacts tel and te2 will energize simultaneously the relays tfl and U2. Opening of break contacts of these same contacts, prevents the energizing of relays tbZ, Z113, tb7 and tb8. The energizing of relay tb4 prevents therefore the energizing of any other piloting relay, and that ensures the selection of the twelve line group, the marking wires of which are multipled upon tb4. This group of twelve lines is made up of the twelve lines reached when the selection bars BS1 to B512 are in positions 1H to 12H and when the bar B813 is at position 13H (see FIGURE 2). This is a part of the lines of the first set. Two other groups of twelve lines of the first set are constituted by lines neighboring the first lines but selected by putting the bar B814 to position 14B (relay tbS) or 14H (relay I126). The fourth group of twelve lines is made up of the lines which, as 15 (FIG. 2), are reached by the bars BS1 to B512 in position 18 to 12B, the bar B513 being in position 13H (relay tbl). When one of the four relays tb4, tb5, rb6 or tb1 energizes, the relay te is still energized, indicating by these means that one of the forty-eight lines of the first set is presently being marked, and is energizing the relays tfl and tf2.

The marked line must be connected to a definite feeder through a primary selector of a predetermined primary multiselector, for instance, the multiselector MP1, of which some circuit-elements are shown upon the left part of the FIG. 4. The circuits of the multiselector MP1, by means of a contact ts, provide a ground to all the terminal multiselectors and particularly to the multiselector MT1. If the terminal selector STl, reached through one of the outlets of MP1, is availableits contact ST1.1 being closedthe closing of contact tfLl causes the energizing of relay tml. The analogous test circuits originating from the other primary multi-selectors and enabling to check the availability of the other selectors such as STl, are multipled before the contact tfLl, and are decoupled by the diodes such as d2. Likewise, if the terminal selector ST2, reached through another outlet of MP1 is available-its contacts ST2.1 being closedthe closing of contact tf2.1 causes the energizing of relay M12. The closure of. tm1.1 tends to energize the relay ml. The closure of contact tm2.1 tends to energize the relay m2. It will be assumed that the relay m1 energizes first. Opening of contact tn1.3 prevents the energizing of relay m2. Thus, the availability of the two selectors utilizable for the connection to be effected is tested by means of relays tml and M12; then, the choice of one out of them is made, by mutual exclusion, between relays ml and m2.

The choice of the selector being accomplished, the closure of a contact such as tn1.2 sends back the received ground to the multiselector MP1, along a wire m2 proper to the selector STl, in order to mark the corresponding outlet and to cause the necessary selection in the multiselector MP1. There exists a contact such as tn1.2 for every selector such as ST1.

During that time, while the energizing of relay tnl signifies that least one terminal selector is available in order to enable the requested connection to be made, the closing of contact 1111.1 commands the accomplishing of the selection in the terminal multiselector MT1. This contactsame as rn2.1 if selector STZ is being usedprovides the ground which enables the energizing of relay to if all the selection bars are in rest position, that is to say if the contacts 1B1 to 14H1 are all in rest condition.

The electromagnet 13H is energized by the following circuit: battery contact tc14-electromagnet 13I-I-con tact tb4.2contact tn1.1-earth. The operating of contact 13H enables the holding of relay to.

The electromagnet 1H is energized by the following circuit: battery-contact tc1-electr0magnet 1Hcontact tb4.3-Wire m1-contact mqmarking earth. The electromagnet 1H holds through its contact 1H1 and cancels the battery for the electromagnets of next ranks, so that if several lines are marked in the group of twelve selected lines by exclusion of the piloting relays, one only among them is selected by chain mounting of the selection electromagnets.

The selection is now terminated. A signal is given by any well known and currently used means, and the connection takes place. A ground applied to wire zcauses the energizing of electromagnet ST1. The connection contacts STlc, corresponding to the selected level, close and ensure the continuity of the wires 01, b, 0, between the multiselector MP1 and the junctor 1A1. The connection is established.

The marking disappears and contact ts opens, and that causes the release of the circuits.

The connection of the same line by means of selector ST2 is operated in the same way, it is established by contacts ST2c.

Now consider the case Where the marking, instead of being accomplished in the junctor IAl, appears in the junctor JAZ. The marking wire of junctor JA2 is connected to the piloting relay I128. The latter energizes. Opening of its contact H18 4 prevents the possible energizing of relay tb7. Opening of contact 2728.1 prevents the possible energizing of the relays tb2 and tb3, whereas the closure of this same contact causes the energizing of relay tfl.

The relay tf2 remains in rest condition and the test operation already described only concerns the terminal selectors such as ST1 upon which is multipled the line [1 equipped with junctor JA2. If the connection has to be established with the multiselector MP1 and the selector ST1 being free-the relay tml energizes followed by relay lnl. The selections take place in the same way as mentioned above but end up with the energizing of electromagnets 1B and 14H. Then the connection is realized and the circuits are released.

It is worth noting that until relay zml energizes, the relays Z174, tbS, tb6 and H91 keep their possibility to energize; but, afterwards, the opening of tm1.2 disconnects their circuit onto battery and this finally will ensure the exclusion; the relay tbS remaining alone operated.

There can be described, in an analogous manner, the connecting of junctor JA3 onto a selection level of the multi-selector MP1. The marking causes the energizing of relays zbZ and then 112. The test of the selectors bears upon those which, like ST2, handle the lines of the third set. If ST2 is free, 2711 2 and M2 energize and the selection accomplishes itself by the energizing of the electromagnet 1B and 14B.

Referring to FIGURE 5, embodiment of the circuits which control the operation of a multiselector such as the one described by FIG. 3, or indicated as MP1 in FIGURE 1 will be described.

Besides the control circuit of the primary multiselector MP1, FIG. shows several elements of the terminal multiselector MT1 circuit, of a control and checking circuit said marker MQ, and of a group of common relays RC.

Each multiselector MP1 selection bar is controlled by two selection electromagnets in charge of putting it in either one of its active positions. They hear the name already given (FIG. 3) to the positions of the bar and are represented by a rectangle diagonally crossed as was the case in FIG. 4. Thus, the selection bar BS1 (FIG. 3) is controlled by the magnets 1B and 1H. Each vertical bar is set to work by a magnet bearing the nameof the selector and represented by a square. The diagram shows the connection magnets CA, CO and CE of the selectors that correspond in FIGURE 2. Above the primary selector connection magnets CA and C0 are four connection contacts bearing the reference mark of the magnet followed by a small letter. These contacts are a simplified representation of the two sets of contacts operating for connection over a determined selection level. For the register finder CE two contacts eel, ce2 represent the two sets of eight contacts which enable connecting the feeder AL to the register EN. Wherever possible the representations and symbology of FIG. 4 are used in FIG. 5.

In this example of embodiment, the adopted operation is the following when a subscriber line is calling, a multi-selector is designated to answer the call under various conditions; a free feeder and register are selected, then connected to one another; the feeder is then connected to the calling subscriber line; later, when the called number has been received by the register, the feeder is connected to the called subscriber line. The control circuits of the multiselector therefore ensure three connections, the first one concerning a register finder, the second, a call finder and the third, a connector. It is clear that the preceding description has only been given as an unrestrictive example and that numerous alternatives may be considered without departing from the scope of the invention, and particularly, the connection of the calling line to the feeder can be effected before the connection of the feeder to a register.

When, for example, a line served by the terminal multi selector MT1 is in calling condition a relay Zp not represented on the diagram energizes and closes its contact lpl.

If it is assumed that the terminal selector ST1 is available, the ground supplied by contact lpl is transmitted, by the contact ST1.5 towards the primary multiselector MP1 to energize relay or in it. The ground is immediately transmitted to other primary multiselectors, under the dependence of the contacts of other available terminal selectors to warn all the primary multiselectors having at its disposal at least one free link with the concerned terminal multiselector.

The primary multiselector MP1 being available, (contact ce5 closed) relay cr energizes. The contact crl closes and establishes the circuit of relay ei.

In each of the registers connected to the outlets of register finders such as CE when they are free, an availability contact such as kll supplies a ground over the marking and availability wire ml. The different wires m l are united in two groups by means of coupling diodes such as d1 or d2, then respectively connected by contacts eyl and e3 2 followed by crl, ek3 and at least one contact CB3 at the winding of relay ei. This circuit enables checking that at least one of the registers is available and at least one of the register finders CE is available. In this case, relay ei energizes. The closure of contact eil supplies a ground which will serve to test the availability of the feeders associated with multiselector MP1.

When feeder AL is free, its contact disp is closed and the call finder CA to which it is connected is at rest. Contact CA5 is then also closed. The ground supplied by contact rail to all the feeders associated to multi selector MP1 and particularly to feeder AL, comes back to multiselector MP1 by the connection wire d connected to the marking and availability wire m2. The different wires such as m2 are united into two groups by means of coupling diodes such as d3 and d4, then respectively connected by contacts ml and cv2 followed by cr2, at the winding of relay ct. Relay ct energizes, which enables noting that multiselector MP1 is able to supply an available feeder and an available register to receive the call. The same thing can occur in one or more other multiselectors such as MP1.

As long as no primary multiselector is particularly designated to answer the call, the common relay 10b (RC) is at rest and its contact obl is closed. In each of the primary multiselectors where relay ct is energized, the closure of contact ctl establishes the circuit of the left winding of a relay cu which energizes. The different energizing circuits of relays cu are connected in parallel which is indicated by a multipling arrow. Each relay cu bears a contact cul which tends to establish a circuit comprising a in series relay ob, the right winding of relay on and relay cv. Relay b energizes and opens its contact obl. The different contacts cu1 are chain connected, so that relay 0b is connected to relays cu and cv only in one primary multiselector where relay cu can be held and relay cv energized. It will be assumed that multiselector MP1 is concerned. In the other n1ulti selectors relay cu which may be energized will release when obl opens.

In multiselector MP1 thus designated to answer the call, the operation of contacts cvl and cv2 switches the marking wires of the feeders towards the pilot relays ebl and eb2. One of these relays energizes, relay 0121 for example, the opening of its contact eb1.3 prevents the energization of relay c112. In the same way, relay eb2, if it energizes prevents the operation of relay e121. Relay ct releases, which has no consequence as long as relay cu holds now not being under control of contact ct1.

Relay ex is energized by the closure of contact eb1.1. It characterizes the fact that a connection feeder register is to be established. The closure of its contacts ex]. and ex2 establishes a circuit which enables checking, by means of relay cc that the selection bars are in rest position. Relay cc energizes by the following circuit: negative terminal of the battery, contacts 1B1 to H1 of the magnets of selection bars BS1 to B510, contact ey3, contacts 11B1 to 13H1 of bars B511 to B813, contact ex2, contacts 14B1 and 14H1 of bar BS14, contacts exl, ey3, cc6, ce2 winding of relay cc, ground. As soon as contact cc6 operates and contact ex3 being closed, relay cc secures for itself a holding circuit in series with the right-hand winding of relay ey which energizes.

The operation of contacts eyl and cy2 switches the marking wires such as m1 coming from registers towards piloting relays eb3 and eb4. It will be assumed, for example, that relay eb3 energizes. The opening of its contact eb3.3 prevents the possible energization of relay eb4. Relay 2124 could have also energized and prevented operation of eb3.

Everything is now in place to put the selection bars in position. As it has already been mentioned in the description relating to FIGURE 3, twenty outlets are reserved for the feeders and eight to the registers over the twentyeight outlets of each register finder. The twenty feeder outlets are selected by means of bars BS1 to B810 set in position by magnets 1B to 10B and in the other position by magnets 1H to 10H. The twenty marking wires such as m2 corresponding to the twenty feeders, are distributed into two groups of ten, according to the position to be given to the selection bars. The energization of relay ebl, choosing a group of ten feeders, connects the ten wires ml to eleetros 1H to 10H.

Relay cc by contacts such as 001 and cc2 also connect the battery to the other terminal of the windings of the selection magnets. One or more magnets 1H to 10H then tend to energize but the feeding battery is connected to the magnets by a contact chain such that when a magnet energizes, it tends to give itself a holding circuit and remove the battery from the magnets placed next to it in the feeding circuit. Thus, assuming that the marking of feeder AL energizes magnet 1H, the operation of contact 1H1 prevents the energization of any other magnet. A feeder is chosen in this way among those that are free, and consequently, marked.

In the same manner, relay c113 connects the marking wires of four registers to magnets 11H and 14H, while the closure of contacts such as 203, cc4, cc5, connect the battery supplied by contact ey3 to the other terminal of the magnets. If it is assumed that the marking of the register EN energizes magnet 11H, the operation of the other magnets is prevented, while magnet 11H secures by 11H1 a hold circuit independent of contact cc3.

Two selection bars are now held in position, one of them selecting a feeder, the other, a register. It is checked by means of relays ce. Contact ex4 being closed, relay cc energizes when one of the contacts 182 to 10H2 is at make and one of the contacts 11B2 to 131 12, 14B2 or 141-12 is also closed. The operation of contact ce2 isolates relay cc which releases. Contacts cs1 to C05 open, and this prevents any other magnet from energizing. The selection achieved is definite.

Relay ex receives a hold circuit by ce4. Relay ey is held on its left winding by cel.

On the other hand, relay ce, by its contact cs3 energizes relay ek, which ensures itself a hold circuit by ekl and 03 3. The connection is immediately controlled by ex8 and ek4. These contacts apply a ground to a chain of contacts CE1 controlled by the connection magnets of the register finders of the multiselector. As soon as by following this chain, one finds a contact at rest, the corresponding magnet is energized. For example, if contact CEl is in rest position, the magnet CE is energized, immediately closes the connection contacts CEc, and prepares a holding circuit through its contact CEZ, on one of the wires that connect the feeder AL to the register EN.

The feeder is now connected to the register. The two units become busy and open their marking circuit, The corresponding selection magnets release. They open the circuit of relay ce which also comes back to rest.

The opening of contact e24 breaks the circuit that held relay ex from the opening of contact ek2. Relay ex releases. It is to be noted that relay cr remains at work because its circuit, held for a moment by ex6 is reestablished by ceS before the release of relay ex. On the contrary, the opening of contact ce1 breaks the holding circuit of relay ey which releases. On the other hand, the opening of contact cxl, after that of contact ell, eliminates the marking ground of the feeders; relay e121 returns to normal, even it other feeders are still available. The opening of contact ek3 having broken the circuit of relay ei the return to rest position of contacts ey1 and @3 2 causes the return to normal of relay e113. Finally, the present partial release of the control circuits of the multiselector MP1 leaves at make only relay cr (a subscriber is calling), cv (MP1 must answer the call) and ek (the connection feeder-register is done). Consequently, relay cg is connected to wire a of the call finders CA, by 0:26 and ek4, waiting for the call of the feeder with a view to selecting the calling line. Contact cv4 being open, connectors such as CO, on the other hand, cannot start the MP1 multiselector circuits.

When the feeder and the register are ready for the selection of the calling line, a short time after the preceding selection, a ground is placed on wire a of the call finder CA thus energizing relay cg. By cgl is immediately checked the availability of marker MQ. If it is free, relay ma is at rest and contact mal is closed. Relay ck can therefore energize and, by its contact ck1, connects in series relay ma, the right-hand winding of relay ck and cl. Relays ma and cl energize while relay ck holds. The marker is seized. Contacts ckl of the different multiselectors are arranged in chain in such a way that only one circuit can establish itself and that the marker can be seized only by one primary multiselector at a time.

The holding of relay cr is ensured by e13 and cr4. That relay cg is ensured by c15.

The marker MQ receives, by cv5 and c14 a ground which energizes mu the contacts of which are not drawn into circuit. It is thus informed that it is seized for calling line selection. By means not represented, the marker marks the calling line(s) and chooses a terminal multiselector having a calling line, if there are several, after checking that there exists a free connection between this multiselector and the primary multiselector MP1. The manner of realizing these operations is well-known in the technique of the art and is outside the scope of the invention that is why, for the sake of clearness, its description can be left out.

If it is assumed that line AB1 served by multiselector MT1 is the only one calling, the latter is automatically designated and a relay tn not represented energizes in it. Contacts such as tnl close and mark the free connections linking the multiselectors MP1 and MT1. The terminal selector ST1 being, for example, assumed free, the pilot relay cbl is energized by the following circuit: battery, cb4, 1cb31, winding of relay cbl, cb2.4, diode d5, marking wire m3, m1, ST16, all. The opening of ch14 prevents the energization of relay cb2 and the operation of contact cbl prevents the energization of ab? and cb4, while causing that of cx.

It has been seen that the primary selectors have 52 levels. The corresponding lines are divided between four groups of thirteen, through intermediary of coupling diodes such as d5. Any marking causes the energization of one of the four piloting relays and one only, as seen for relay 0111.

The closure of contacts cxl and cx2 establishes the circuit that enables checking, by means of relay cc that the selection bars are in rest position. Relay cc energizes by the following circuit: battery-contacts 1B1 to 10H1, contact ey3, contacts 11B1 to 13H1, contacts cxl, contacts 14H1 to 14B1, contacts cx2, contact ce2, relay cc, ground. Relay cc energizes and the operation of its contact cc6 ensures holding circuit, contact cx3 being closed. An independent feeder battery is also applied in direction of magnets 14B and 14H by cx3, cc6, cx2 and C05. As previously described, relay cc by its contacts, connects the feeding battery to the windings of other selection magnets. On the other hand, relay cbl by thirteen contacts such as cb13 connects thirteen marking wires to th selection magnets IE to 13H. It would be the same for thirteen other marking wires if cb2 were at make. The choice between the two selected lines by the same bar is effected by serving the bar BS14. For thirteen lines which cause the energization of cbl, the contact 0121.2 energizes the magnet 14H, whereas for the lines which cause the energization of relay c122, 14B is energized. Relays cb3 and cb4 are concerned with the two groups of thirteen lines obtained with the aid of 1H at 13H; 14H and 14B are energized by correspondence.

If it is assumed that the terminal selector ST1 is reached by line l1 (see FIG. 3), wire m3 is connected by cb1.3 to the magnet 18 which energizes and secures a hold circuit by 1B1. The operation of this contact also removes the feeding battery of the following magnets up to 13H. None of them can energize.

One of the selection bars BS1 to B813 and bar BS14 are maintained in position and, contact cx4 being closed, relay ce can energize by one of the contacts 1B2 to 10H2, or 11B2 to 13H2 and 14BZ or 14H2, in the present example by IE2 and 14H2. The operation of C62 breaks the circuit of relay cc which releases and supplies the battery for the holding of 14H. Contacts ccl to cc open. When the selection is over it cannot be changed. On the other hand, contact cl2 being also closed, relay mm of marker MQ energizes in parallel over relay ce. By contacts not represented, it indicates that selection is prepared in multiselector MP1.

Marker MQ also supervises the selection of line AB1 in multiselector MT1. When the selection is over, it comes into communication with register EN through feeder AL by wire fc connected to wire c of the call finder CA by contact (:16. Signals are exchanged between the marker and the register, concerning particularly the kind of selected line. Then, the register orders the connection. For that, the ground is placed on Wire 1 of the call finder. The connection magnet CA energizes. It closes the connection contacts CAc, then operation contacts CA1 and CA5. Wires a, b, c, t of the feeder are connected to the terminal selector ST1. The magnet ST1 also energizes and connects wires a, b, c, t of the feeder to wires a, b, c, t of the subscriber line AB1. The connection of the calling line to the feeder is done.

As soon as contact CA5 is open the circuit of relay cg is broken. It de-energizes and breaks the marker seizure circuit. Relay c1 releases and the marker is released. The opening of 013 breaks the circuit of relay cr which also de-energizes. The opening of 013 breaks the circuit of relays 0b, cu, cv which de-energize, followed by all the circuits. As soon as relay ob is back to normal a new ca1ling line can be served by a primary multiselector. As soon as contact ceS is closed, the multiselector MP1 can be used for handling a new call. As soon as contacts cs6 and c114 are closed, relay cg is connected to wire a of the connectors and can be seized for called line selection as will now be described.

The calling line being connected to the feeder AL, itself connected to the register EN, the subscriber receives the dial tone then dials the called subscribers number. The register receives the digits and stores them until the called line selection can be done.

To select the called line, a register, through the feed junctor, causes the seizure of the associated primary multiselector control circuits, thus, for MP1,. if no calling line selection is in process, relay cg is connected to wire a of the connectors by ce6 and cv4. For the seizure, wire a of the feeder AL is grounded and relay cg energizes.

The marker is seized immediately by the closure of contact cgl as previously described. Relay c1 energizes and, by e16 connected the wire fc of marker to wire 0' of feeder AL, which enables the register to communicate with the marker, and, particularly, to transmit it, by channels not represented an indication which ldefines which is the subscriber line to be selected. This line is marked and, in the terminal multiselector that serves it, relay in energizes. Assuming that it is MT1, the free channels between multiselectors MT1 and MP1 are marked and the multiselector selection bars MP1 are set in place as described. The indication of end-of-selection is given to the marker. Later on, the connection is ordered by register EN. A ground is then received over wire it of the register. The connection magnet CO energizes, closes its contacts COc, then CO1 to CO4 and thus connects wire a, b, c, l, of the feeder to wires a, b, c, t, of the terminal selector. The latter is also connected by the ground on wire t' connected to t.

The release is done as previously described, from the break of the relay cg circuit, the relay releases, which releases one after the other all the circuits.

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

We claim:

1. A selection system having multiselector switches for interconnecting calling and called lines, said multiselector switches grouped into a plurality of sequential selector stages including a primary and a terminating stage, common equipment including feeder means and register means associated with the multiselector switches of said primary stage, means for connecting said lines to the outlets of the multiselector switches of said terminating stage, means for connecting the outlets of the multiselector switches of a prior sequential stage to the inlets of the multiselector switches of the next sequential stage, each of said multiselector switches comprising selectors and selector levels, certain of said selector levels being split, register-finder means including said split selection levels of said primary multiselector switches for selectively interconnecting said feeder means and said register means, and means including said split selector levels on the multiselector switches of said terminating stage for connecting certain of said outlets to only a portion of said selectors.

2. A selection system using multiselector switches for interconnecting calling lines to desired called lines, said system having said multiselector switches arranged in groups including a primary group and a terminating 115 group, said multiselector switches of the terminating group comprising a plurality of selectors, first selection level means enabled to connect to all of said selectors on the same multiselector switch, second selection level means enabled to connect to part of the selectors of said same multiselector switch, and third selection level means enabled to connect to the rest of said selectors on the same multiselector switch, and means for connecting certain of said lines to said first selection level means and means for connecting other of said lines to said second and third selection level means.

3 A selection system for connecting calling lines to called lines using multiselector switches arranged in sequential groups including a primary group and a termi nating group, means for connecting subscriber lines to outlets on the multiselector switches in said determinating group, means for connecting the outlets of the multiselector switches in said primary group to the inlets of the multiselector switches of said terminating group, means including selectors and selection levels for connecting outlets to selected inlets, said selection levels including split selection levels whereby the lines connected to said split levels are not available to all of the selectors in the multiselcctor switch.

4. The selection system of claim 3 wherein means are provided for connecting a first set of large trafiic lines to selection levels available to all of the selectors on the multiselector switches and for connecting smaller traffic lines to split selection levels available to only certain of the selectors.

5. The selection system of claim 4 wherein the smaller traflic lines are arranged into a second and third set and wherein means are provided for connecting lines from said second and third sets to outlets connected to different portions of said split selection levels.

6. The selection system of claim 5 wherein means are provided for multipling all the homologous outlets of the terminal group that are coupled to said first set.

7. The selection system of claim 6 wherein means are provided for multipling the lines of said second set to the outlets of part of the selectors and the lines of said third set to the outlet of the remainder of the selectors.

8. The selection system of claim 5 wherein means are provided operated responsive to a marking on a line for testing the availability of the part of said selectors available through said split connection level.

9. A selection system for connecting calling lines to called lines comprising at least one primary selector stage, said selector stage including a plurality of multiselector switches having inlets and out-lets, feeder means connected to the inlets of said multiselector switches, register means, register finder means integrally associated with each of said multiselector switches for connecting said register means to said feeder means under control of said selection system.

10. The selection system of claim 9 wherein said inlets are connected to primary selectors, means for connecting calling lines to said feeder means through certain of said primary selectors and means for connecting the feeder means to selected ones of said called lines through other of said primary selectors.

11. The selection system of claim 10 wherein said register finder means comprises definite selectors on said multiselector switches, said definite selector having a first and a second group of outlets, means for connecting said feeder means to one of said first group of outlets, means for connecting register means to one of said second group of outlets, and means for simultaneously selecting the outlet of said first and said second group to connect said feeder means to said register means.

12. The selection system of claim 11 wherein means are provided for multipling the homologous outputs of said second group.

13. The selection system of claim 1 wherein means are provided for multipling individual registers of said register means to at least two multiselector switches.

14. The selection system of claim 11 wherein switching means operated responsive to the selection of a free register means and a free feeder means for preventing the further selection of free register means and feeder means and for preparing the multiselector switch to connect the feeder means to the calling line are included in said multiselector switches.

References Cited UNITED STATES PATENTS 2,999,131 9/1961 Edstrom 17922 3,290,447 12/1966 Ohno 17922 3,313,888 4/1967 Ohno 179-22 KATHLEEN H. CLAFFY, Primary Examiner.

LAURENCE A. WRIGHT, Assistant Examiner. 

